Intermittently actuated mechanism



3 Sheets-Sheet l ffZ/L T H LJUNGGREN ETAL INTERMITTENTLY ACTUATED MECHANISM Feb. 20, 1951 Filed Oct. 25, 1945 Jig 02a T H LJUNGGREN EI'AL INTERMITTENTLY ACTUATED MECHANISM Feb. 20, 1951 Filed Oct. 25; 1945 Feb. 20, 1951 "r. H. \LJUNGGREN ETAL I 2,542,821

INTERMITTENTLY ACTUATED MECHANISM Filed Oct. 25, 1945 s Sheets-Sheet s Patented Feb. 20, 1951 2,542,821 INTERMITTENTLY ACTUATED MECHANISM Thor H. Ljunggren, Charlestown, N. IL, and Forrest A. Johnson, Springfield, Vt., assignors to Bryant Chncking Grinder Company, Springfleld, Vt., a corporation of Vermont Application October 25, 1945, Serial No. 624,452

6 Claims. 1 This invention relates to mechanism for intermittently moving a movable member by very small increments, as, for example, the movable member may be a feed carriage for feeding a tool and work relatively. Preferably the mechanism is of a type in which the frequency of actuation may be varied readily within wide limits and in which the extent of motion of the member moved at each actuation may be accurately very small. A further object of the invention is to provide a ratchet mechanism by which very small and accurate step by step motions of the driven member may be made.

A further object of the invention is to arrange a limiting traveling element in such a way that it travels substantially slower than a shaft,

actuating a feed screw, making it possible to arrange the feed mechanism for every fine incremental feed and at the same time allow for a large over-all range of the power feed movement.

Still another object of the invention is to provide a feed mechanism where the power feed is terminated at a predetermined position when a traveling element in the mechanism makes contact with a positive stop. This movable element is so arranged that further movement either in the feed direction or in a feed retracting direction can be made by hand without the element losing contact with the positive stop.

Still another object of the invention is to provide such a mechanism adapted to be actuated by a timing mechanism and independent of the position of the member being moved.

For a complete understanding of this invention, reference may be had to the accompanying drawings in which Figures 1 and 2 are fragmentary front elevations and top plan views, respectively, of a grinding machine showing the mounting and actua tion of the grinding wheel carriage.

Figure 3 is a sectional view on line 33 of Figure 2.

Figure 4 is an electrical diagram of an electronic actuating'mechanism,

Figures 5 to 8, inclusive, are detail sectional views on the correspondingly numbered section lines of Figure 3.

Figure 9 is a detail sectional view on line M of Figure 5.

Figure 10 is a view similar to a portion of Figure 7, but with the latch element in inoperative angular position.

Referring first to Figures 1 to 3, at I is indicated the bed of a grinding machine on which is supported a cross sliding carriage 2, this carriage as shown supporting a grinding wheel driving unit comprising a motor 3 driving a shaft 4, this shaft carrying the grinding wheel 5 on its end. The cross slide 2 is supported on a pair of spaced bars 6 extending across a casing l2 and the carriage 2 is operatively connected to a feed screw I, by the rotation of which the slide or carriage 2 is moved back and forth on the slide bars 6.

For the purpose of this invention the feed screw 1 carries a worm wheel 8 (see Figure 3) with which meshes a worm 9 fixed to a feed shaft Ill. The feed shaft i0 is journaled in bearings i I and I la in the casing l2 extending upwardly from the bed I and also extends into a housing ll secured to the casing I2. Within the housing It the shaft ID has keyed thereto the hub l5 of a ratchet wheel i6, and rockable on the bushing l5a. on the hub l5 and between a pair of spacing washers I1, is a rock member 20. This rock member has pivoted thereto at 2| four arms 22 spaced around its axis and extending about and enclosing a ratchet wheel l6. As shown best in Figure 6, the ratchet wheel It has teeth, each of which has one steep face 24 and a less steep face 25, all the teeth facing in the same direction around the axis of the shaft I'll. As shown there are twenty-five ratchet teeth. Cooperating with these teeth are four spring-pressed ball detents 26 spaced equally around the periphery of the ratchet wheel and each housed within a socket 21 in the free end of one of the arms 22. Each is pressed toward the ratchet wheel as by a spring 28 bearing against the corresponding arm 22 and ,within a socket 29 of the rock member and backed up by a threaded closure plug 30.

It will be noted that with the four detents and twenty-five ratchet teeth, the detents are spaced incommensurate with the teeth so that only one detent is in position at one time to engage fully between adjacent teeth of the ratchet wheel. Thus as shown the left hand detent 26 is so engaged while each of the others is more or less retracted. The detent in engagement is then in driving relation to a steep face 24 on the ratchet wheel [6 so that when the rock member 20 is rocked clockwise it will turn the ratchet wheel it. Each of the detents is wedged back against a spring on the reverse rocking motion of the rock member 20 by virtue of lesser steepness of face so that the ratchet wheel I 6 does not turn at the reverse motion of the rock member 20. With this arrangement a very precise extent of motion forwardly of the ratchet wheel is produced by each rocking action so that the extent of each angular motion of the feed shaft I is accurately controlled in accordance with the extent of rocking of the rock member. In the arrangement shown an amplitude of rocking oscillation of the member 20 sufficient only to bring the several detents successively into operative relation will produce one hundredth of a revolution of the shaft I0 at each complete double oscillation. The rock member 20, as shown best in Figure 9, is provided with a pin 300 projecting therefrom which extends into a slot 3i of a reciprocating member 32 by the reciprocation of which the rock member is given its rocking motions in opposite directions.

As shown in Figure 5, the member 32 comprises a rod which extends slidably through a bushing 33 through a wall of the housing I4. Its lower end is connected to the slidable core 35 of an electromagnet 36. Its upper end extends into a tubular casing 31 and its threaded into a bushing 38 within this casing, the bushing bearing against a coil spring 39 surrounding the bar 32 and reacting between the bushing and a base 40 of the casing 31 through which the bar 32 passes. The casing 31 is shown as threaded into the upper end of the housing I4. The bushing 38 has a head 42 by which it may be turned to adjust the pressure exerted by the spring 39 and its normally covered by a cap 43 which may be secured to the upper end of the bar 32 as by a set screw 44. It will be evident that by alternately energizing and deenergizing the solenoid 36, the rock member 20 may be rocked back and forth, the pull of the solenoid rocking it in one direction and the pull of the spring 39 returning it, and the adjustment of the sleeve 31 in the casing will serve to determine the point from which the start of the rocking motion begins.

Means are provided by which the total normal extent of power feed may be limited and in accordance with which nearly four full turns of the shaft I0 may be had. To this end the shaft II has keyed thereto a pinion 50 within the housing I4, and this pinion meshes with three planetary pinions i, each journaled on a pin 52 and 52a projecting from a spider 53 Journaled on a bushing 54 surrounding shaft I0. The planetary pinions II also mesh with an internal gear ring 56 positioned between a pair of friction disks 51 and 58. The disk 51 bears against a shoulder 59 on the inner wall of the casing I4, and the disk 58 is pressed against the gear ring by a pair of Belleville washers 55 engaged by the inner end of a head '60 threaded into the outer end of the casing I4. One of the pivots of the planetary pinions 5|, as 52a, projects through the spider and may impinge upon a stop rod 65 slidably mounted within a guide tube 66 projecting within the casing I4, the outer end of this rod 65 when pressed to the left, as viewed in Figures 7 and 10, actuating a stop switch 68. This switch is normally closed and after rod 05 has been pushed the switch will open and stay in this position until reset button 65a is pushed, when the switch returns to its normally closed position. Before contacting the stop rod 65, the pin 52a engages and lifts a latch element I0 pivoted at H between a pair of Jaws 12 of a rock shaft I3. This latch element I0 is mounted on one side of the axis of the rock shaft 13 so that when this axis is turned from the position shown in Figure '7 into that shown in Figure in clockwise direction viewed from its outer end through 90, its end is raised above the pin 520 so that the pin 52a may be retracted as will later appear. In the position shown in Figure 'I, it acts by gravity to prevent retraction of the element 52a from the stop rod 65 when it has once reached stopping position. A pin I4 projecting from the casing I4 into a segmental cutout I5 of a knurled actuating knob 16 secured to the outer end of the rock shaft 13 defines the rocking limits of the rock shaft.

Reverse rotation of the shaft I0 may be accomplished at any time by grasping and turning a hand knob 80 secured to the outer end of the shaft I0, the detents 26 being pressed back when such turning is effected. The knob 80 is shown as threaded onto the outer end of a cylindrical block 8| through which the shaft l0 passes and to which it is secured as by a nut 52 threaded on its outer end and lying within a recess 83 in the outer end of the block 8|. The block 8| is keyed to the shaft ID. A plurality of outwardly spring pressed balls 84 riding in radial sockets 85 within the block 8| engage a v internal groove 86 in a sleeve 81 and frictionally hold the sleeve 81 to turn with a knob 80. This sleeve 81 may be provided with peripheral graduations thereon cooperating with a stationary index finger 88, so that after the sleeve has been set in the desired angular relation to the block 6|, the extent of its rotation may be indicated by change in the indicator marks coming opposite to the pointer 88.

The mechanism may also be given a hand controlled feed motion, after the stop has acted to prevent further power feed. This is done by turning the knob 80 in feed direction, this acting through the engagement of the pinions 5| thereon to turn the internal gear 56 between its friction holding disks 5! and 58, the member 53 with its pinion pivots 52 and 52a being held stationary by reason of the engagement of the pivot 52a against the stop rod 65 and its stationary surrounding guide tube 86. During this action the detents engaging the ratchet wheel I6 are wedged back successively by the faces of the ratchet teeth which engage them.

The ratchet mechanism hereinbefore described is adapted to be actuated, without reference to or control by the member being moved, by a timing mechanism which alternately energizes and de-energizes the solenoid 35. While such timing mechanism is per se not a part of our invention, for the purpose of illustration an electronic timing mechanism particularly suited for this purpose is illustrated in Figure 4. Two triode tubes with indirectly heated cathodes are shown at TI and T2. Governing the grid circuits of these tubes are separate potentiometers Pi and P2. The tube anode circuits control the relays RI and R2. Relay RI has a double throw switch element I00 with contacts a and 2). Relay R2 has a single throw switch element IOI with the contact c. Current is taken from a suitable source of supply through leads I02 and I03 and a main switch I04 to the primary of a transformer I05. The secondary I06 of the transformer supplies energy to the relays RI and R2 and a separate secondary winding I01 supplies heating current to the cathodes of the tubes TI and T2. Contact a connects through the lead I08 with one side of the solenoid 36, the other side leading back through lead I08 and the knock-oil switch 68 and lead IIO to the line I02 inwardly of the main switch I04.

Assuming the switch I04 to be closed and with the relay contacts as shown, the contact 0 being closed, places the grid GI of the tube TI at zero potential. Therefore the tube TI is conducting and the relay RI will become energized and close the contact at b, opening the contact at a. Contact b when closed removes negative potential from the delay network of the tube T2, this delay network including the potentiometer P2 and the condenser Ill, allowing the charge of this condenser to leak of! through the potentiometer P2 until the negative voltage at the grid G2 of tube T2 no longer controls anode current and relay R2 becomes de-energized. This allows the grid condenser N2 of the tube TI to build up its negative charge so that the anode of Ti no longer conducts and relay RI becomes de-energized, closing the contact a which operates the solenoid 38. As the relay R2 is opened, contact 0 closes, removing the negative potential of the delay network of the tube Tl so that after the delay relay BI is energized, again closing the contact at b and opening that at a. This removes the negative potential from the delay network of the tube T2 after negative potential leaks from the condenser Ill. The anode then passes current and the relay R2 operates as before. The potentiometer P2 is as a rule adjusted once and for, all through a time delay suited to give the solenoid core ample time after the energization of the solenoid 36 to travel the whole length of its path and set against the pole piece. This potentiometer can then be located on the tube and relay panel in the control cabinet of the machine as it is only adjusted at rare intervals. The potentiometer P2 is intended to govern the energizing frequency of'the solenoid by way of impressing on the grid an impulse of variable intensity which is dependent upon the setting of the potentiometer P2. The control of this potentiometer should therefore be at a point easily accessible to the operator and is shown One of the several methods by which this feed mechanism can be utilized is as follows. The

grinding wheel is brought in contact with the I work piece and the power feed is started. Grinding is now automatic as the grinding wheel is reciprocating past and in contact with the work piece and the power actuated feed moves the wheel at predetermined time intervals by small increments against the work until the traveling element 52a on the spider for the planetary gearing hits the stop 65 at the predetermined amount of travel. This arrests further movement of the power feed by operating the switch I. This is apparent to the operator from the fact that the cap 43 ceases its up and down movement. The wheel may be backed off at once, or it can be allowed to dwell during a "spark out" period. In either case the dial 8! is set on zero at pointer 88. The tool and work piece are separated, this completing the rough grinding operation. The work piece has now been cleaned up and on it has been generated a surface with a reasonably high degree of finish as to circular form, straightness, and dimension, leaving just enough stock to be removed in a later finishing operation intended to impart a specifled fine dimensional tolerance and surface finish. When wheel and work are separated, a truing device, commonly a diamond point, is placed in the path of the wheel to true it and make it keen and accurate for the finish grinding. Any amount dressed off the wheel is compensated for by turning the hand wheel 80 the desired amount and thereafter resetting the dial .1 to zero.

The wheel is then returned to the work for the finishing operation, during which the hand wheel is moved in feeding direction by the amount required to produce the final work sizes desired. After finish operation the driving element 82a is released by operating the latch II and this element 52a can now, by means of the liand wheel 80, be returned to its initial posit on.

From the foregoing description of an embodiment of this invention, it should be evident to those skilled in the art that various changes and modifications might be made without departing from the spirit or scope of this invention.

We claim:

1. In combination with a rotary feed shaft, an internal gear concentric with said shaft, friction means normally holding said internal gear stationary. a gear fixed to said shaft in the plane of said internal gear, a planetary gear between and meshing with said internal gear and said fixed gear, a spider to which sad planetary gear is loumaled, power means for turning said shaft, an element carried by said spider, a stop for said turning means located in the path of motion of said element to be actuated by impingement thereon of said element at a predetermined angular position of said element, and manually operated means for turning said shaft in normal feed direction while said element is stationary, the turning of said shaft then turning said internal gear against the action of said friction means by the rotation of said planetary gear.

2. In combination with a rotary feed shaft, an internal gear concentric with said shaft, friction means normally holding said internal gear stationary, a gear fixed to said shaft in the plane of said internal gear, a planetary gear between and meshing with said internal gear and said fixed gear, a spider to which said planetary gear is journaled, power means for turning said shaft, an element carried by said spider, a stop for said turning means located in the path of motion of said element to be actuated by impingement thereon of said element at a predetermined angular position of said element, manually operated means for turning said shaft in normal feed direction while said element is stationary, the

turning of said shaft then turning said internal gear against the action of said friction means by the rotation of said planetary gear, latch means engageable with said element and normally preventing said element from being retracted from said predetermined position, and means for releasing said latch means to permit said shaft to be turned in reverse direction while said internal gear is stationary.

3. In combination with a rotary feed shaft, power means for turning said feed shaft step by step, means for stopping said power feed at a predetermined feed position of said shaft, said means including a spider rotatable on said shaft, reduction gearing from said shaft to said spider. an element carried by said spider, and means engageable by said element at a predetermined angular position of said spider for stopping rotation of said spider in either direction.

' 7 an element carried by said spider, means engageable by said element at a predetermined angular position of said spider for stopping rotation of said spider in either direction, said gearing including a friction connection, a yieldable connection interposed between said power means and said shaft, and an operator-actuable means for turning said shaft, said friction and yieldable connections permitting said shaft to be turned in either direction at any time by said operatoractuable means regardless of said power means and said stopping means.

5. In combination with a rotary feed shaft, a normally stationary internal gear concentric with said shaft, a gear fixed to said shaft in the plane of said internal gear. a planetary gear between and meshing with said internal gear and said shaft-carried gear, a spider to which said planetary gear is Journaled, an element carried by said spider, means for turning said shaft, a stop for said turning means located in the path of motion of said element to be actuated by impingement thereon of said element at a predetermined position of said element, and means actuatable to rotate said planetary gear and said internal gear while said turning means is stationary.

6. In combination with a rotary feed shaft, an internal gear concentric with said shaft, friction means normally holding said internal gear stationary, a gear fixed to said shaft in the plane of said internal gear, a planetary gear between and meshing with said internal gear and said fixed gear, a spider to which said planetary gear is journaled, power means for turning said shaft, an element carried by said spider, a stop for said turning means located in the path of motion of said element to be actuated by impingement thereon of said element at a predetermined angular position of said element, and manually operated means for turning said shaft in either direction while said element is stationary, the turning of said shaft then turning said internal gear against the action of said friction means by the rotation of said'planetary gear.

THOR H. IJUNGGREN.

FORREST A. JOHNSON.

ant-masons crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 377,413 Smith Feb. 7, 1888 953,192 Brinkman Mar. 29, 1910 1,185,092 Head May 30, 1916 1,392,325 Hansen Oct. 4, 1921 1,767,593 Laabs June 24, 1930 1,767,752 Friedl June 24, 1930 1,832,189 De Giorgi Nov. 17, 1931 1,930,160 Crilly Oct. 10, 1933 2,010,528 Schoileld et a] Aug. 6, 1935 2,048,467 Roehm July 21, 1936 2,334,581 Pyne Nov. 16, 1943 2,334,724 Paessler Nov. 23, 1943 2,365,059 Decker Dec. 12, 1944 2,391,470 May Dec. 25, 1945 2,420,552 Merrill May 13, 1947 FOREIGN PATENTS Number Country Date 307,460 Germany Aug. 28, 1918 

